Nimesulide incorporated lipid micropheres: An approach to targeting and controlled release

Nimesulide, a non-steroidal antiinflammatory drug with very short biological half-life was encapsulated within lipid microspheres by a modified solvent evaporation method with an aim of targeting the drug to the site of inflammation and for controlled release. Physiological lipids such as glyceryl tristearate, cholesterol were used instead of synthetic polymer matrix materials. The prepared lipid microspheres were evaluated with respect to particle size distribution, encapsulation efficiency, in vitro release behaviour and in vivo antiinflammatory activity in rats. Lipid microspheres with a suitable average particle size of 6-7μm could be prepared with this method. The drug was released continuously over 12 days with no burst effect with a maximum release of 74%. The in vivo drug release was investigated in rats, by measuring antiinflammatory activity using cotton pellet granuloma method. A single administration of lipid microspheres showed a better antiinflammatory activity when compared to equivalent multiple administrations of the standard nimesulide solution. The drug concentration was higher in the tissues at the site of inflammation of lipid microspheres treated rats. These results indicated the possibility of drug being released at a controlled rate from lipid microspheres and targeted at the inflamed cells.